[fuchsia] Convert Gfx PlatformView to use modern TouchSource API (flutter#35018)

Original PR: flutter#32877

Revert of flutter#32877: commit 1965c92 (flutter#33471)

*This* patch: Revert of flutter#33471

fxbug.dev/85125

Author: jaeheon

shell/platform/fuchsia/flutter/engine.cc

@@ -166,8 +166,8 @@ void Engine::Initialize(
   } else {
     gfx_protocols.set_view_focuser(focuser.NewRequest());
     gfx_protocols.set_view_ref_focused(view_ref_focused.NewRequest());
-    // TODO(fxbug.dev/85125): Enable TouchSource for GFX.
-    // gfx_protocols.set_touch_source(touch_source.NewRequest());
+    gfx_protocols.set_touch_source(touch_source.NewRequest());
+    // GFX used only on products without a mouse.
   }
   scenic->CreateSessionT(std::move(gfx_protocols), [] {});
 

shell/platform/fuchsia/flutter/platform_view.cc

@@ -109,33 +109,31 @@ PlatformView::PlatformView(
   });
 
   // Begin watching for pointer events.
-  if (is_flatland) {  // TODO(fxbug.dev/85125): make unconditional
-    pointer_delegate_->WatchLoop([weak = weak_factory_.GetWeakPtr()](
-                                     std::vector<flutter::PointerData> events) {
-      if (!weak) {
-        FML_LOG(WARNING) << "PlatformView use-after-free attempted. Ignoring.";
-        return;
-      }
+  pointer_delegate_->WatchLoop([weak = weak_factory_.GetWeakPtr()](
+                                   std::vector<flutter::PointerData> events) {
+    if (!weak) {
+      FML_LOG(WARNING) << "PlatformView use-after-free attempted. Ignoring.";
+      return;
+    }
 
-      if (events.size() == 0) {
-        return;  // No work, bounce out.
-      }
+    if (events.empty()) {
+      return;  // No work, bounce out.
+    }
 
-      // If pixel ratio hasn't been set, use a default value of 1.
-      const float pixel_ratio = weak->view_pixel_ratio_.value_or(1.f);
-      auto packet = std::make_unique<flutter::PointerDataPacket>(events.size());
-      for (size_t i = 0; i < events.size(); ++i) {
-        auto& event = events[i];
-        // Translate logical to physical coordinates, as per
-        // flutter::PointerData contract. Done here because pixel ratio comes
-        // from the graphics API.
-        event.physical_x = event.physical_x * pixel_ratio;
-        event.physical_y = event.physical_y * pixel_ratio;
-        packet->SetPointerData(i, event);
-      }
-      weak->DispatchPointerDataPacket(std::move(packet));
-    });
-  }
+    // If pixel ratio hasn't been set, use a default value of 1.
+    const float pixel_ratio = weak->view_pixel_ratio_.value_or(1.f);
+    auto packet = std::make_unique<flutter::PointerDataPacket>(events.size());
+    for (size_t i = 0; i < events.size(); ++i) {
+      auto& event = events[i];
+      // Translate logical to physical coordinates, as per
+      // flutter::PointerData contract. Done here because pixel ratio comes
+      // from the graphics API.
+      event.physical_x = event.physical_x * pixel_ratio;
+      event.physical_y = event.physical_y * pixel_ratio;
+      packet->SetPointerData(i, event);
+    }
+    weak->DispatchPointerDataPacket(std::move(packet));
+  });
 
   // Configure the pointer injector delegate.
   pointer_injector_delegate_ = std::make_unique<PointerInjectorDelegate>(

shell/platform/fuchsia/flutter/platform_view_unittest.cc

@@ -1394,8 +1394,7 @@ TEST_F(PlatformViewTests, OnShaderWarmup) {
   EXPECT_EQ(expected_result_string, response->result_string);
 }
 
-// TODO(fxbug.dev/85125): Enable when GFX converts to TouchSource.
-TEST_F(PlatformViewTests, DISABLED_TouchSourceLogicalToPhysicalConversion) {
+TEST_F(PlatformViewTests, TouchSourceLogicalToPhysicalConversion) {
   constexpr std::array<std::array<float, 2>, 2> kRect = {{{0, 0}, {20, 20}}};
   constexpr std::array<float, 9> kIdentity = {1, 0, 0, 0, 1, 0, 0, 0, 1};
   constexpr fuchsia::ui::pointer::TouchInteractionId kIxnOne = {

shell/platform/fuchsia/flutter/pointer_delegate.cc

@@ -447,7 +447,9 @@ void PointerDelegate::WatchLoop(
   // Start watching both channels.
   touch_source_->Watch(std::move(touch_responses_), /*copy*/ touch_responder_);
   touch_responses_.clear();
-  mouse_source_->Watch(/*copy*/ mouse_responder_);
+  if (mouse_source_) {
+    mouse_source_->Watch(/*copy*/ mouse_responder_);
+  }
 }
 
 }  // namespace flutter_runner